Nidāna-sthāna, the second section of Vāgbhaṭa’s Astāṅga-Hṛdaya (7th century CE), crystallizes centuries of Charaka–Suśruta learning into a compact clinical manual. Devoted to nidāna (causation) and samprāpti (pathogenesis), it systematically describes disease names, etiologies, prodromes, cardinal signs and prognosis—most famously treating jvara (fever) and systemic disorders. Key themes are doshic imbalance, stages of disease evolution, diagnostic criteria (roga-lakṣaṇa), and preventive insight. Written for bedside decision-making, its concise algorithms and emphasis on individualized causation remain strikingly relevant: they inform modern clinical reasoning, lifestyle medicine, and integrative approaches to chronic, metabolic, and epidemic illnesses.